This invention relates generally to ocean thermal energy conversion systems and more particularly to a closed cycle system for converting heat sources of low to moderate differential temperatures into usable energy.
The nation's greatly increased concern for the efficient utilization of our energy resources has stimulated the development of systems and associated equipment to convert the energy from waste heat sources or low level heat sources, to useful mechanical or electrical power.
Among the systems which have been developed are those utilizing the available temperature difference between a heat source source and a heat sink such as those which utilize the difference between the temperature of ocean surface waters and the deeper and cooler below surface waters generally in tropical areas which systems are classified as ocean thermal energy conversion systems, hereinafter OTEC Systems. In these OTEC Systems, generally the available temperature difference between the heat source which is the ocean surface waters and the heat sink which is the deeper and cooler below surface waters will be in the order of 40.degree. F. or greater.
Heretofore, certain prior art closed cycle systems for recovering the heat energy from such differential temperature in ocean waters have been designed and developed such as is shown in U.S. Pat. Nos. 2,006,985; 3,995,160; 4,083,189; 4,014,279; 3,967,449; and 2,595,164.
Some of these systems are highly desirable because they utilize water as the thermo-dynamic working fluid. Water as the thermo-dynamic working fluid offers a number of advantages over other thermo-dynamic working fluids. It is a high heat transfer fluid that operates at low pressures (15 PSIG) and in temperature ranges generally in the order of 70.degree. F. to 250.degree. F. for the water vapor temperature. These characteristics permit the use of low cost heat transfer equipment and structures, which has the further advantage in that current technology of such associated heat transfer equipment and apparatus is well developed and substantiated. Further, water is a low cost working fluid and permits the use of conventional materials of construction, presents minimal environmental problems, offers low maintenance cost, and minimal safety consideration.
The present invention seeks to provide an improved closed cycle system for generating usable energy more particularly from the ocean thermal energy available in ocean waters in which the structure and operation is primarily based on the use of water as the thermo-dynamic working fluid for driving a turbine which is operatively mounted on and associated with an evaporator-condenser unit so designed that the evaporating section and the condensing section have a common wall and includes, a U-shaped seal and transfer passage therebetween so as to simplify construction and permit the operative interrelation and function of these sections in accordance with the operating demands of the associated steam or gas turbine mounted thereon.
The present improved closed cycle system for generating usable energy also includes means for generating distilled water for makeup to the system or for use outside of the system.